1. Field of the Invention
The present invention relates to a carrier transporting apparatus and a method of transporting a carrier on which devices under test, such as integrated circuits (hereinafter, simply referred to as “ICs”), are loaded. As an example, such a carrier transporting apparatus is useful to be adapted to an automatic handler. An automatic handler loads assembled devices under test on a carrier for supplying the devices under test to a test section automatically. Thereafter, the automatic handler takes out the devices under test from the carrier, and then automatically sorts and accommodates the devices in accordance with results of the test.
2. Description of Related Art
Firstly, a carrier transporting method using an automatic handler that employs an carrier transporting apparatus in the earlier technology will be schematically explained. FIG. 1 is a plane view for illustrating a carrier transporting method using an automatic handler. As shown in FIG. 1, a large number of assembled devices under test such as ICs are disposed on a supply tray 1 in a loading section 2. The devices under test are shifted from the supply tray 1 onto a carrier 4 in a supply section 3 (see FIG. 4) by suction and suction release operation of a supply hand 5. The carrier 4 has plate-like shape and has a large number of recesses to accommodate ICs. After shifting the ICs onto the carrier 4, an entrance shutter 13 of a thermostat 15 is opened, and the carrier 4 is carried in a preheat section 5 in the thermostat 15 through the opened entrance shutter 13. The entrance shutter 13 is closed after the carrying in. The ICs loaded on the carrier 4 are heated or cooled to a predetermined temperature in the preheat section 5. After the preheating, the carrier 4 is transported to a measuring section 6 inside the thermostat 15, and each of the ICs loaded on the carrier 4 is tested by an IC tester (not shown) under a condition of the predetermined temperature condition. The carrier 4 with the tested ICs is transported to a drying chamber 7 in the thermostat 15 and then heated and dried. This drying operation is performed to prevent dewing of the carrier 4 and the ICs outside the thermostat 15 when the carrier 4 is cooled.
After the drying by heating, an exit shutter 14 of the thermostat 15 is opened, and the dried carrier 4 is carried out from the thermostat 15 to a buffer section 8. The exit shutter 14 is closed after the carrying out. In the buffer section 8, a direction of transporting the carrier 4 is changed to a direction that crosses a carrying-out direction in which the carrier 4 is carried out from the thermostat 15, that is a direction towards a supply section 3, so that the carrier 4 is transported to a accommodation section 9. In the accommodation section 9, the ICs on the carrier 4 are sorted and accommodated on an accommodation tray 12 in an unloader section 11 by suction and suction release operation of an accommodation hand 10, in accordance with results of the test in the thermostat 15. The empty carrier 4 is transported to the supply section 3. By repeating the above-described steps, ICs are successively tested, sorted and accommodated in accordance with results of the test.
During the steps where the carrier 4 is carried out from the thermostat 15 and transported to the accommodation section 9 or the supply section 3, it is required that the direction of transporting the carrier 4 is changed to the direction which crosses the carrying-out direction in the buffer section 8.
Hereinafter, the structure of principal portions of the earlier developed carrier transporting apparatus and a method of changing the transporting direction thereof will be explained with reference to FIGS. 7A and 7B. As shown in FIGS. 7A and 7B, the earlier developed carrier transporting apparatus comprises a carrying-out direction guide 19 and a cross direction guide 18. The carrying-out direction guide 19 guides a carrier 4 in a carrying-out direction when the carrier 4 is carried out from a thermostat 15. After the carrier 4 is guided by the carrying-out direction guide 19 and transported to the buffer section 8, the cross direction guide 18 guides the carrier 4 in a cross direction that is a direction to cross the carrying-out direction, when the carrier 4 is transported in the cross direction.
The carrying-out direction guide 19 and the cross direction guide 18 are configured to be separately moved upward and downward by a cylinder 23. When the carrier 4 is carried out, the cross direction guide 18 is moved downward to wait at a predetermined position so that the cross direction guide 18 will not obstruct the carrier 4. On the other hand, the carrying-out direction guide 19 is previously moved upward to wait at another predetermined place (see FIG. 7A). Therefore, the carrying-out direction guide 19 can receive the carrier 4 from the thermostat 15 while the carrier 4 is held horizontal. The carrier 4 is guided by the carrying-out direction guide 19 and carried out to the buffer section 8, while the carrier 4 is held horizontal during these operations, as shown in FIG. 7A. Thereafter, in order to transport the carrier 4 in the cross direction successively, the carrying-out direction guide 19 is moved downward to a predetermined position and the cross direction guide 18 is moved upward to another predetermined position previously.
Practically, the carrier 4 is moved downward with the carrying-out direction 19 section of the way, and received by the cross direction guide 18 before the carrying-out direction guide 19 reaches to the predetermined position. The carrying-out direction guide 19 is continuously moved downward to the predetermined position, so that the carrying-out direction guide 19 does not obstruct the carrier 4 during the cross direction transportation (see FIG. 7B). When the carrier 4 is shifted from the carrying-out direction guide 19 to the cross direction guide 18, the cross direction guide 18 holds the carrier 4 with hold guides 18a. In this way, after the carrier 4 is shifted to the cross direction guide 18, while the carrier 4 is guided by the hold guides 18a of the cross direction guide 18, the carrier 4 is transported in the cross direction.
However, the earlier developed carrier transporting apparatus as described above requires an elevator mechanism, such as the cylinder 23 or the like, for moving the guides upward and downward so that the carrier 4 is shifted from the carrying-out direction guide 19 to the cross direction guide 18, and a space for such an elevator system is also required. Moreover, the carrier 4 can not be carried out from the thermostat 15 until completion of the step of moving upward the carrying-out direction guide 19 to a position for receiving the carrier 4 and the step of moving downward the cross direction guide 18 to a position where the cross direction guide 18 does not obstruct the carrier 4. As a result, it takes considerable time to carry out the carrier 4. Furthermore, the carrier 4 can not be transported in the cross direction until completion of the step of shifting the carrier 4 by moving downward the carrying-out direction guide 19 and moving upward the cross direction guide 18 and the step of moving downward the carrying-out direction guide 19 to a position where the carrying-out direction guide 18 does not obstruct the carrier 4. As a result, it takes considerable time to carry out the carrier 4.